Content Delivery Networks (CDNs) receive content from an origin web server. CDNs contain tiers of caching in order to distribute and store copies of content throughout the network. Adaptive video content may be distributed using standard HTTP methods over traditional CDNs. Client devices using adaptive video bitrate methods generally request a manifest file from the origin server periodically in order to have an accurate list of available video segments. Manifest files get quickly distributed through the network due to a relatively small file size and a short time to live (TTL) property. The TTL property of objects over HTTP is used to ensure certain objects in a network are refreshed. In adaptive video streaming, the manifest file should be refreshed often while the actual video segments do not need to be refreshed often.
CDNs typically support a feature called invalidation. Invalidation is used when content needs to quickly be removed from the network in the case of censoring content, breech in security, invalidating corrupted content, or to purge test content when setting up for a live event. Traditional invalidation uses an out-of-band message to be sent to invalidate content in the caches of the network. A specific object name must be known ahead of time when sending an invalidation command. The command is sent throughout the nodes in the network allowing each node to invalidate the cached content. Completing the invalidation depends on the number of object URLs included in the invalidation request, a time to propagate the invalidation signal and a time to properly invalidate all objects. The invalidation request uses the object names of all the segment files. There may be hundreds or thousands of content segment files cached throughout the network depending on the duration of the video.
It would be desirable to implement content delivery network video content invalidation through ABR manifest manipulation and signaling to provide faster invalidation of objects throughout the network.